New tennis player

Hi. I've just started playing tennis due to my girlfriend large interest in the sport. Obviously at the moment I can't hit the ball too well so am pathetic when trying to have a rally/game

I started playing with a good player i know who's giving me tips and "training" me and also I won 3 hours with a good coach in the UK (milton keynes) which I have got coming up.

I still feel though that as I'm a new player i'll be very poor as such etc..

What major tips would you recommend for a brand new player to do.. What are the most important things to consider for example? My backhand swing is very inconsistent and un-natural as I tend to snatch at the ball rather thna play a smooth swing, and my serve is also rather inconsistent too, struggling sometimes to even get it over the net (though I'm 5ft8ish)

I am considering buying your dvd's but feel im in too early stages for that and should wait till after the coaching sessions before i carry on training myself using your dvd's.

Thanks for any advice you can give me, I'm really keen to improve as a player and been able to play good tennis.